1. Field of the Invention
The present invention relates in general to a transmission for reversing the rotational direction of a drive shaft and, more particularly, low cost, long wearing transmission for reversing the direction of a drive shaft.
2. Description of the Prior Art
Transmissions assemblies for reversing the drive direction of a drive shaft are known in the art. The general configuration of such transmission assemblies are a drive shaft secured to a toothed gear. Such transmissions typically include a load shaft also secured to a toothed gear. A counter shaft gear set is also provided to transfer torque from the drive shaft to the load shaft. Shift forks are used to slide the load shaft to bring various toothed gears of the load shaft into contact with various toothed gears of the countershaft. A reverse gear shaft is also provided to transfer torque between the countershaft and load shaft in a direction opposite that resulting from a direct transfer of power between the countershaft and load shaft.
In prior art transmission assemblies, the transfer of power using toothed gears often leads to premature wear, a build-up of metal filings in the transmission case, a loss of efficiency associated with missing teeth, and a complex transmission including synchronizers, bearings, gaskets, rings, seals, bolts and the like. Such prior art assemblies require an extensive amount of machining and are costly to assemble. Maintenance on such prior art assemblies is time consuming and costly, and drastically increases as such prior art transmission assemblies age.
Additionally, prior art transmissions of torque using toothed gears leads to a relatively high level of friction and loss motion, thereby decreasing the efficiency of such transmissions.
Prior art transmissions, therefore, have numerous disadvantages, including high costs of production and maintenance, and lowered efficiency. It would be desirable to provide an improved transmission assembly, costing less to produce and maintain and more efficiently transferring power from a drive shaft to a load shaft. The difficulties encountered in the prior art discussed hereinabove are substantially eliminated by the present invention.
In an advantage provided by this invention, a transmission assembly alternatively translates linear actuation into torque on a load shaft in a first direction to torque on the load shaft in the opposite direction.
Advantageously, this invention provides a transmission assembly having a small number of parts.
Advantageously, this invention provides a transmission assembly with low maintenance requirements.
Advantageously, this invention provides a transmission assembly of compact size.
Advantageously, this invention provides a transmission assembly with low cost, easily machinable parts.
Advantageously, this invention provides a transmission assembly of a durable and longwearing construction.
Advantageously, in a preferred example of this invention, a transmission assembly is provided, comprising an overrunning clutch assembly, comprising a race having an inner annular contact surface, a plurality of sprags provided along the inner annular contact surface of the race, the plurality of sprags defining a drive space, means for retaining the plurality of sprags along the inner annular contact surface of the race, a shaft having a drive portion with a drive diameter sufficient to cause rotation of the shaft in response to a rotation of the race when the drive portion is positioned at least partially within the drive space, and means for moving the drive portion of the shaft at least partially into and out of the drive space.